DPMS will not work on RedHat 7.1. I have 2 different machines, 1 a fresh
install and the other an upgrade from 7.0. Same symptoms, both machines.
Option "DPMS" is in the Monitor section of the file /etc/X11/XF86Config-4
file. However, when at the login screen for Gnome the monitor never shuts
down. If I login and do an "xset q" I get:
...
DPMS (Energy Star):
Standby: 10 Suspend: 10 Off: 10
DPMS is Disabled
...
Of course I could have xset turn on DPMS each time a user logs in, but
that's not all that useful to me. I need DPMS to blank when at the login
screen.

See the same thing.
I believe this is due to xscreensaver. Even when you don't check the box for
"power management",
xscreeensaver resets X's DPMS settings. and it never does seem to kick in when
enabled anyway..
If I don't fire up xscreensaver at all DPMS works as expected.

I had the same problem on two different machines. I generated a new
/etc/X11/XF86Config-4 file using Xconfigurator, and the problem appears to have
been solved. The monitor now powers down properly both with and without the
screensaver. I use KDE rather than gnome, which may have an effect on the
solution. See bug #37025 for details.

DPMS works for me fine in both GNOME and KDE, and with KDM/GDM. I'm not
using it from a default install however. IMHO, anaconda might be setting
DPMS to off by default? I dunno, but I don't see any bug with DPMS in
XFree86. I'll let the installer team decide what to do with this one.

I'd agree that it seems to be installer related, at least in my case. The
installer did not add option "DPMS" to my config file. In bug #37025 (perhaps
this bug should be marked a duplicate of bug #37025?) I've attached copies of
both the installer and Xconfigurator generated files.

I really don't think it's the installer. I've used my own XF86Config-4, and
it's had Option "DPMS"
the whole time. It's either something in XFree or something in xscreensaver.
Try this:
- make sure DPMS is enabled in the XF86Config
- turn off xscreensaver (tell control-center "no screensaver")
- restart X
- "xset q", examine the DPMS settings. if you wait long enough ti will kick
in
- xscreensaver &
- "xset q", examine the DPMS settings. They are all set to 10. Wait
forever. Monitor will not turn off.
I've seen this on multiple machines with different X configs. I'm going to go
scrub the settings again
and compare with Xconfigurator's output, but I know for sure I've had it turned
on in all cases.

My origingal situation was NOT a duplicate of bug #37025, because Anaconda DID
add "DPMS" to XF86Config-4 but DPMS still did not work. It did not work at all
until I run XConfigurator manually after the install. I do however agree that
it is likely to be an anaconda issue.
As for Gnome/KDE, this is an issue with xscreensaver. Now that I've gotten DPMS
to work with after the XConfigurator runs, DPMS gets disabled when I enable
xscreensaver whether I've selected "Power Management" or not.
IMHO this should be split into 2 bugs, one for the anaconda folks and one for
the xscreensaver folks.

I'm now running xscreensaver-3.32-1, and control-center-1.4.0.1-2. Bug still
exists, though manifestation has changed slightly. Instead of changing dpms
settings to 10/10/10, it now does the following (no matter what is entered into
the "screensaver" section of gnome control-center):
DPMS (Energy Star):
Standby: 7200 Suspend: 7200 Off: 14400
DPMS is Disabled
This bug is is more than a cosmetic problem, since it results in many users
being required to physically turn off/on their monitors multiple times each day.
In addition to being an inconvenience, the repeated degaussing causes increased
wear on the monitor.

This bug is very annoying and needs to be fixed very soon. On my system, the
following worked:
(1) Manually add DPMS entries to /etc/X11/XF86Config (without the "-4" at the
end). This fixes DPMS when nobody is logged on. Unfortunately, xscreensaver
disables DPMS when somebody IS logged on.
(2) For each user, run xscreensaver-demo and change "Screensaver Options". This
generates the ~/.xscreensaver file, where DPMS parameters for the xscreensaver
are set.
BTW, this applies to xscreensaver-3.29-3 and XFree86-4.0.3-5, which are the
current versions. Other related bugs are #37025 and #37721.

Ok, as josip(at)icase.edu points out, this is a new "feature" of xscreensaver:
Changes since 3.30: * Put in more sensible defaults for DPMS, and updated
the documentation to reflect the fact that all your
DPMS settings are now belong to xscreensaver.
Apparently, gnome control-center doesn't know about this. Fixing it should
simply being a matter of making gnome control-center add the line:
dpmsEnabled: True
to the user's ~/.xscreensaver when he/she turns on power management.

I am seeing this as well. I am running KDE and have the screensaver disabled.
For good measure, I created a .xscreensaver file:
dpmsEnabled: True
and re-started X. However, "xset q" still reports "DPMS is Disabled".